The present invention relates to the general field of stepper motors and of the methods for controlling the position of such motors.
In particular, such motors, operating in a rotary movement, are used to command the movements of the distribution shutters in the heating, ventilation and air conditioning systems of motor vehicles, often called HVAC systems.
As is known, stepper motors move the air distribution shutters between two extreme positions in which stops limit the movement of this movable member. The position of the motor is then checked relative to the stops.
This operation generally gives satisfaction. However, it has been noted that errors of position of the motor are easily introduced during blocking events. In particular, it is necessary to carry out a blocking of several motor steps on the stops in order to locate them. The final position is therefore not sure and the locating procedure may be relatively long which is very often detrimental. Errors of rotational direction are also observed without it being possible to detect them.
In addition, these stepper motors do not make it possible to determine a shorter path from one position to another because, to go from one point to another, it may be necessary to make a virtually complete revolution.